Efficacy of Osimertinib in Patients with Lung Cancer Positive for Uncommon EGFR Exon 19 Deletion Mutations

EGFR-Mutant Urothelial Carcinoma Harboring an Ala750_Ile759delinsGlyGly Alteration with a Primary Resistance to Polychemotherapy and a Sensitivity to Osimertinib: A Literature Review on EGFR Alterations and Response to EGFR Tyrosine Kinase Inhibitors in Cancers

Urothelial carcinoma is three to four times more common in men than in women, with a 73-year old mean age at diagnosis which is older than the average age at diagnosis of all cancers. Urothelial carcinoma is rare in people under 40 years of age. Smoking, exposure to industrial chemicals, and family history influence the development of bladder cancer, but age remains one of the most important risk factors. It is well established that women are more likely to be diagnosed with an advanced disease, impacting the prognosis and a higher stage-for-stage mortality compared to men. A gender difference is also observed when considering molecular features; for example, there a higher male/female ratio in Fibroblast Growth Factor Receptor 3 (FGFR3)-mutated bladder cancer. Epidermal Growth Factor Receptor (EGFR) amplifications, which are roughly depicted in 25-50% of urothelial carcinoma, have been correlated with a worse prognosis. Genomic alterations of clinical interest are mainly Human Epidermal Growth Factor Receptor 2 mutations and amplifications, as well as FGFR 3 alterations; however, no EGFR mutation has been routinely reported despite the frequency of its amplifications. Recurrently, no targeted inhibitors have demonstrated a benefit compared to platinum-based chemotherapy. We report a rare case of a 35-year-old woman presenting bone, hepatic, and lymph node metastatic urothelial carcinoma, harboring a deletion of 24 nucleotides in exon 19 of the EGFR gene with a 5-month response to osimertinib, a third-generation EGFR tyrosine kinase inhibitor.

Advanced lung adenocarcinoma harboring uncommon EGFR 19 Del and T790M/trans-C797S mutations after resistance: a case report and literature review

The most common epidermal growth factor receptor (EGFR) mutation in non-small cell lung cancer (NSCLC) is exon 19 deletion (19del), which is sensitive to EGFR tyrosine kinase inhibitors (EGFR-TKIs). However, uncommon EGFR 19del mutations exhibit varied responses to EGFR-TKI treatment. Research and clinical data on these uncommon subtypes are limited. Additionally, resistance to EGFR-TKIs is inevitable. EGFR C797S is a frequent mechanism of resistance to third-generation EGFR-TKIs, usually occurs in cis with T790M and in 5% of patients in trans. Here, we report a patient diagnosed with lung adenocarcinoma harboring EGFR 19Del L747-A755delinsSKD mutation with co-occurring T790M and trans-C797S mutations, who showed a positive response to combination therapy with first- and third-generation TKIs. This case report suggests an effective treatment option for such patients.

Strategies to Overcome Resistance to Osimertinib in EGFR-Mutated Lung Cancer

Non-small-cell lung cancer (NSCLC) represents the most common type of lung cancer. The majority of patients with lung cancer characterized by activating mutations in the epidermal growth factor receptor (EGFR), benefit from therapies entailing tyrosine kinase inhibitors (TKIs). In this regard, osimertinib, a third-generation EGFR TKI, has greatly improved the outcome for patients with EGFR-mutated lung cancer. The AURA and FLAURA trials displayed the superiority of the third-generation TKI in both first- and second-line settings, making it the drug of choice for treating patients with EGFR-mutated lung cancer. Unfortunately, the onset of resistance is almost inevitable. On-target mechanisms of resistance include new mutations (e.g., C797S) in the kinase domain of EGFR, while among the off-target mechanisms, amplification of MET or HER2, mutations in downstream signaling molecules, oncogenic fusions, and phenotypic changes (e.g., EMT) have been described. This review focuses on the strategies that are currently being investigated, in preclinical and clinical settings, to overcome resistance to osimertinib, including the use of fourth-generation TKIs, PROTACs, bispecific antibodies, and ADCs, as monotherapy and as part of combination therapies.

Optimizing Osimertinib for NSCLC: Targeting Resistance and Exploring Combination Therapeutics

Non-small-cell lung cancer (NSCLC) is a leading cause of cancer-related deaths worldwide, with epidermal growth factor receptor (EGFR) mutations present in a substantial proportion of patients. Third-generation EGFR tyrosine kinase inhibitors (EGFR TKI), exemplified by osimertinib, have dramatically improved outcomes by effectively targeting the T790M mutation-a primary driver of acquired resistance to earlier-generation EGFR TKI. Despite these successes, resistance to third-generation EGFR TKIs inevitably emerges. Mechanisms include on-target mutations such as C797S, activation of alternative pathways like MET amplification, histologic transformations, and intricate tumor microenvironment (TME) alterations. These resistance pathways are compounded by challenges in tolerability, adverse events, and tumor heterogeneity. In light of these hurdles, this review examines the evolving landscape of combination therapies designed to enhance or prolong the effectiveness of third-generation EGFR TKIs. We explore key strategies that pair osimertinib with radiotherapy, anti-angiogenic agents, immune checkpoint inhibitors, and other molecularly targeted drugs, and we discuss the biological rationale, preclinical evidence, and clinical trial data supporting these approaches. Emphasis is placed on how these combinations may circumvent diverse resistance mechanisms, improve survival, and maintain a favorable safety profile. By integrating the latest findings, this review aims to guide clinicians and researchers toward more individualized and durable treatment options, ultimately enhancing both survival and quality of life for patients with EGFR-mutated NSCLC.

Safety and Efficacy of Osimertinib in Patients With Non-Small-Cell Lung Cancer and Uncommon Tumoral Epidermal Growth Factor Receptor Mutations: A Systematic Review and Single-Arm Meta-Analysis

PURPOSE

The activity of osimertinib is not fully characterized in non-small-cell lung cancer (NSCLC) with uncommon epidermal growth factor receptor (EGFR) mutations. Therefore, we conducted a systematic review and meta-analysis to assess the safety and efficacy of osimertinib in patients with NSCLC harboring uncommon somatic EGFR mutations.

METHODS

PubMed, Embase, and the Cochrane Library were searched for eligible studies reporting the efficacy and safety of osimertinib in NSCLC with uncommon EGFR mutations defined as any mutations other than exon 19 deletion, L858R and T790M mutations, and exon 20 insertion, except when in compound. Then, we performed a meta-analysis to pool survival outcomes and antitumoral activity, including intracranial (ic) response and adverse events.

RESULTS

Fifteen studies comprising 594 patients were included. The most frequently observed uncommon solitary mutations were G719X in 25% (81/327) of patients and L861Q in 21% (69/327). The most common compound mutations were G719X with T790M in 12% (23/192) of patients and G719X with S768I in 11% (22/192). Pooled analysis showed an objective response rate (ORR) of 51.30% (95% CI, 45.80 to 56.81), a disease control rate (DCR) of 90.11% (95% CI, 86.27 to 92.96), a median progression-free survival of 9.71 months (95% CI, 7.96 to 11.86), and a median overall survival of 16.79 months (95% CI, 9.93 to 28.39). icORR was 45.96% (95% CI, 30.18 to 62.17), and icDCR was 95.76% (95% CI, 69.84 to 100). Osimertinib was well tolerated with a frequency of grade 3 or more adverse events of 21.77% (95% CI, 6.24 to 43.33).

CONCLUSION

Osimertinib demonstrated robust response in NSCLC harboring uncommon EGFR mutations, without unanticipated safety concerns.

From Rarity to Reality: Osimertinib's Promising Horizon in Treating Uncommon EGFR Mutations in Non-Small Cell Lung Cancer

In the realm of advanced non-small cell lung cancer (NSCLC) harboring epidermal growth factor receptor (EGFR) therapy with tyrosine kinase inhibitors (TKI), addressing optimal treatment for uncommon EGFR mutations like G719X in exon 18, S768I in exon 20, and L861Q in exon 21 remains a pivotal yet challenging frontier. Contrary to the well-established efficacy of EGFR-TKIs in common EGFR mutations, these uncommon alterations pose unmet medical needs due to a lack of comprehensive evidence. While afatinib, a second-generation EGFR-TKI, has received FDA approval for patients with these uncommon EGFR mutations, the approval was based on a post-hoc analysis of randomized clinical trials. Recent developments include multiple clinical trials investigating the efficacy of both second- and third-generation EGFR-TKIs in patients with uncommon EGFR mutations. A noteworthy example is a prospective phase II trial of osimertinib including the landmark UNICORN study, which has shown promising results in treating uncommon EGFR mutations. Despite various reports on the efficacy of afatinib and osimertinib in treating uncommon EGFR mutations, the appropriate use of these TKIs remains unclear. This review aims to consolidate the findings from the latest clinical trials focused on uncommon EGFR mutations, outlining variations in the therapeutic efficacy of these TKIs based on the specific genetic mutation. By synthesizing these findings, we aim to guide oncologists toward more informed decisions in employing TKIs for NSCLC with uncommon EGFR mutations other than exon 20 insertion. Additionally, we explore potential treatment strategies tailored to these patient populations to address the challenges posed by these mutations.

Current status of molecular diagnostics for lung cancer

The management of lung cancer (LC) requires the analysis of a diverse spectrum of molecular targets, including kinase activating mutations in EGFR, ERBB2 (HER2), BRAF and MET oncogenes, KRAS G12C substitutions, and ALK, ROS1, RET and NTRK1-3 gene fusions. Administration of immune checkpoint inhibitors (ICIs) is based on the immunohistochemical (IHC) analysis of PD-L1 expression and determination of tumor mutation burden (TMB). Clinical characteristics of the patients, particularly age, gender and smoking history, significantly influence the probability of finding the above targets: for example, LC in young patients is characterized by high frequency of kinase gene rearrangements, while heavy smokers often have KRAS G12C mutations and/or high TMB. Proper selection of first-line therapy influences overall treatment outcomes, therefore, the majority of these tests need to be completed within no more than 10 working days. Activating events in MAPK signaling pathway are mutually exclusive, hence, fast single-gene testing remains an option for some laboratories. RNA next-generation sequencing (NGS) is capable of detecting the entire repertoire of druggable gene alterations, therefore it is gradually becoming a dominating technology in LC molecular diagnosis.

First-line Osimertinib for Lung Cancer With Uncommon EGFR Exon 19 Mutations and EGFR Compound Mutations

Introduction

Up to 20% of EGFR-mutated NSCLC cases harbor uncommon EGFR mutations, including atypical exon 19 and compound mutations. Relatively little is known about the efficacy of osimertinib in these cases.

Methods

Patients treated with first-line osimertinib for NSCLC with rare EGFR exon 19 (non E746_A750del) or compound mutations were included. Response assessment and time to progression were determined using Response Evaluation Criteria in Solid Tumors version 1.1 criteria. Kaplan-Meier analyses were used to estimate progression-free survival (PFS), time to treatment discontinuation (TTD), and overall survival (OS).

Results

Thirty-seven patients with NSCLC harboring an atypical EGFR exon 19 mutation or compound mutation were treated with first-line osimertinib at Johns Hopkins from 2016 to 2021. Overall response rate (ORR) was 76% and median PFS, TTD, and OS were 13 months (95% confidence interval [CI]: 10-15), 22 months (95% CI: 17-32) and 36 months (95% CI, 29-48), respectively. Among atypical exon 19 mutations (n = 25), ORR was 80%, median PFS was 12 months (95% CI: 10-15), median TTD was 19 months (95% CI: 17-38), and median OS was 48 months (95% CI: 25-not reached). Compound mutations (n = 12) had an ORR of 67%, median PFS of 14 months (95% CI: 5-22), median TTD of 26 months (95% CI: 5-36), and median OS of 36 months (95% CI: 20-46). Twelve patients (32%) continued first-line osimertinib after local therapy for oligoprogression.

Conclusions

Osimertinib exhibited favorable outcomes for rare EGFR exon 19 and compound mutations. The heterogeneity in outcomes among these groups of tumors with similar mutations underscores the need for continued reporting and further study of outcomes among rare variants to optimize management for each patient.

Assessment of RAS-RAF-MAPK Pathway Mutation Status in Healthy Skin, Benign Nevi, and Cutaneous Melanomas: Pilot Study Using Droplet Digital PCR

In the present study, we employed the ddPCR and IHC techniques to assess the prevalence and roles of RAS and RAF mutations in a small batch of melanoma (n = 22), benign moles (n = 15), and normal skin samples (n = 15). Mutational screening revealed the coexistence of BRAF and NRAS mutations in melanomas and nevi and the occurrence of NRAS G12/G13 variants in healthy skin. All investigated nevi had driver mutations in the BRAF or NRAS genes and elevated p16 protein expression, indicating cell cycle arrest despite an increased mutational burden. BRAF V600 mutations were identified in 54% of melanomas, and NRAS G12/G13 mutations in 50%. The BRAF mutations were associated with the Breslow index (BI) (p = 0.029) and TIL infiltration (p = 0.027), whereas the NRAS mutations correlated with the BI (p = 0.01) and the mitotic index (p = 0.04). Here, we demonstrate that the "young" ddPCR technology is as effective as a CE-IVD marked real-time PCR method for detecting BRAF V600 hotspot mutations in tumor biopsies and recommend it for extended use in clinical settings. Moreover, ddPCR was able to detect low-frequency hotspot mutations, such as NRAS G12/G13, in our tissue specimens, which makes it a promising tool for investigating the mutational landscape of sun-damaged skin, benign nevi, and melanomas in more extensive clinical studies.

RELAY, Erlotinib Plus Ramucirumab in Untreated, EGFR-Mutated, Metastatic NSCLC: Outcomes by EGFR Exon 19 Deletion Variants

Introduction

EGFR gene mutations are drivers of NSCLC. The RELAY double-blind, placebo (PBO)-controlled phase 3 study revealed superior progression-free survival (PFS) for ramucirumab plus erlotinib (RAM + ERL) versus PBO (PBO + ERL) in patients with untreated advanced NSCLC and an EGFR-activating mutation. This exploratory analysis evaluated potential associations between EGFR exon 19 deletion (ex19del) variants and clinical outcomes.

Methods

Patients (N = 449) were randomized (1:1) to RAM plus ERL or PBO plus ERL. Plasma samples were collected at baseline, on treatment, and at 30-day post-study treatment discontinuation follow-up. Baseline and treatment-emergent gene alterations were investigated by Guardant360 next-generation sequencing. Patients with a valid baseline plasma sample and ex19del were included (RAM + ERL, n = 62; PBO + ERL, n = 72).

Results

The most common ex19del variant was E746_A750del (67.2%); EGFR E746 deletions (E746del) occurred more frequently than L747 deletions (74.6% versus 25.4%, respectively). TP53 mutations were the most frequently co-occurring baseline gene alterations. With treatment arms combined, median PFS was 18.0 months versus 12.5 months for patients with uncommon (non-E746_A750del, n = 44) versus common (E746_A750del, n = 90) ex19del variants (hazard ratio [HR] = 1.657 [95% confidence interval or CI:1.044-2.630]). Median PFS was longer with RAM plus ERL versus PBO plus ERL for patients with the common (15.2 versus 9.9 mo; HR = 0.564 [95% CI: 0.344-0.926]) and E746del (15.4 versus 9.9 mo; HR = 0.587 [95% CI: 0.363-0.951]) variants. Treatment-emergent post-progression EGFR T790M rates were higher in the common versus uncommon and E746del versus L747 deletion subgroups.

Conclusions

RAM plus ERL provides benefit and improves treatment outcomes for patients with metastatic NSCLC with EGFR ex19del variants.

A destabilizing Y891D mutation in activated EGFR impairs sensitivity to kinase inhibition

EGFR tyrosine kinase inhibitors (TKIs) have transformed the treatment of EGFR-mutated non-small cell lung carcinoma (NSCLC); however, therapeutic resistance remains a clinical challenge. Acquired secondary EGFR mutations that increase ATP affinity and/or impair inhibitor binding are well-described mediators of resistance. Here we identify a de novo EGFR Y891D secondary alteration in a NSCLC with EGFR L858R. Acquired EGFR Y891D alterations were previously reported in association with resistance to first generation EGFR TKIs. Functional studies in Ba/F3 cells demonstrate reduced TKI sensitivity of EGFR L858R + Y891D, with the greatest reduction observed for first and second generation TKIs. Unlike other EGFR mutations associated with TKI resistance, Y891D does not significantly alter ATP affinity or promote steric hindrance to inhibitor binding. Our data suggest that the Y891D mutation destabilizes EGFR L858R, potentially generating a population of misfolded receptor with preserved signaling capacity but reduced sensitivity to EGFR inhibitors. These findings raise the possibility of protein misfolding as a mechanism of resistance to EGFR inhibition in EGFR-mutated NSCLC.

Non-small cell lung cancer cells with uncommon EGFR exon 19delins variants respond poorly to third-generation EGFR inhibitors

BACKGROUND

This study compared the clinical efficacy of first-, second-, and third-generation tyrosine kinase inhibitors (TKIs) in previously untreated non-small cell lung cancer (NSCLC) patients harboring uncommon epidermal growth factor receptor (EGFR) exon 19delins variants.

METHODS

We retrospectively analyzed the clinical outcomes of NSCLC patients with EGFR exon 19delins mutations who were treated with third- and first-generation EGFR TKIs. In vitro and in vivo studies were conducted to verify the sensitivity of these mutations to distinct generations of TKIs. Molecular simulation was used to investigate the structural characteristics of the EGFR mutant molecules.

RESULTS

In a multicenter cohort of 1,526 patients, 37 (2.4 %) had uncommon EGFR 19delins mutations. Twenty-four patients were treated with first-generation EGFR TKIs, and third-generation TKIs were administered to ten patients as frontline therapy. Patients carrying EGFR exon 19delins mutations who were given third-generation TKIs exhibited comparatively shorter progression-free survival (PFS) and overall survival (OS) in relation to those who received first-generation EGFR inhibitors; median PFS: 6.9 months vs. 19.1 months (p < 0.001), Median OS: 19.1 months vs. 32.6 months (p < 0.001). In vivo and in vitro studies revealed that uncommon EGFR 19delins variants exhibit limited sensitivity to third-generation EGFR inhibitors in contrast to first- and second-generation EGFR inhibitors. The molecular binding affinity of third-generation EGFR TKIs toward uncommon EGFR 19delins mutations was less than that of first- and second-generation EGFR inhibitors.

CONCLUSIONS

Uncommon EGFR 19delins variants respond poorly to third-generation EGFR inhibitors in NSCLC. Uncommon EGFR 19delins mutations may serve as an unfavorable predictive factor for the efficacy of third-generation EGFR TKI therapy, offering potential guidance for future clinical decision-making.

Circ_16601 facilitates Hippo pathway signaling via the miR-5580-5p/FGB axis to promote my-CAF recruitment in the TME and LUAD progression

BACKGROUND

Lung cancer represents a significant public health issue in China, given its high incidence and mortality rates. Circular RNAs (circRNAs) have been recently proposed to participate in the development and progression of tumors. Nevertheless, their particular roles in the pathogenesis of lung adenocarcinoma (LUAD), the tumor microenvironment (TME), and the underlying molecular mechanisms are still not well understood.

METHODS

High-throughput sequencing was used to analyze the circRNAs expression profiles in 7 pairs of human LUAD tissues. shRNA was used to knockdown the YAP1 and FGB genes. RNA sequencing and RT-qPCR were performed to classify the regulatory effects of circ_16601 in LUAD cells. The progression effect of circ_16601 on lung cancer was investigated in vitro and in vivo.

RESULTS

The circ_16601 is significantly elevated in LUAD tissues compared to adjacent normal lung tissues, and its high expression is positively associated with poor prognosis in LUAD patients. Additionally, circ_16601 overexpression promotes LUAD cell proliferation in vitro and increases xenograft tissue growth in mice in vivo; circ_16601 also could recruit fibroblasts to cancer associate fibroblasts. Mechanistically, circ_16601 can directly bind to miR-5580-5p, preventing its ability to degrade FGB mRNA and enhancing its stability. Subsequently, circ_16601 promotes the activation of the Hippo pathway in a YAP1-dependent manner, leading to LUAD progression.

CONCLUSIONS

Our findings shed valuable insights into the regulatory role of circ_16601 in LUAD progression and highlight its potential as a diagnostic and therapeutic target in LUAD. Overall, this study provides theoretical support to improve the prognosis and quality of life of patients suffering from this devastating disease.